The invention relates to an exhaust gas heat exchanger for motor vehicles, of the same type which is known from commonly assigned DE-A 199 07 163. The invention also relates to a method for production of an exhaust gas heat exchanger such as this.
DE-A 199 07 163 discloses a welded exhaust gas heat exchanger which comprises a housing casing, a pipe or tube bundle and pipe bases (header plates), with the ends of the pipes being welded in the pipe bases and the pipe bases being welded via circumferential beads to the housing casing. The pipe ends are welded in the pipe base at the ends, while the pipe bases are welded circumferentially to the housing casing, that is to say the laser beam which is used for the welding process is directed at right angles to the pipe axes. In this case, the laser beam is either passed around the housing or the laser beam is stationary and the housing is rotated about its longitudinal axis. The different welding directions (with respect to the direction of the laser beam) make it necessary to clamp the workpiece, that is to say the heat exchanger block, at least twice successively. This increases the production complexity. Furthermore, in the known production method, provision is made for the heat exchanger block, that is to say the housing casing, not to be cut to length until two circumferential weld beads have been applied, to be precise by means of an additional laser beam step. This also involves additional production complexity.
One object of the present invention is to improve the welding carried out on an exhaust gas heat exchanger of the type mentioned initially. Another object of the invention is to provide a simplified method for its production, in particular for welding of this exhaust gas heat exchanger.